1. Continuous Surrogate Monitoring for Pollutant Load Estimation in Urban Water Systems Anthony A. Melcher, USU Civil and Environmental Engineering, UWRL Jeffery S. Horsburgh, USU Civil and Environmental Engineering, UWRL Bryce Mihalevich, USU Civil and Environmental Engineering, UWRL Phil Suiter, USU Civil and Environmental Engineering, UWRL
This work was funded by iUTAH and the Utah Water Research Laboratory
How Can We Quantify Pollutant Loads from Urban Stormwater Runoff?
Background
Study Area
Urban stormwater catchments experience high-volume runoff events and shorter times to peak discharge due to developed landscapes and impervious areas
Total Suspended Solids (TSS) and total phosphorus (TP) pollutant loading events are of short duration and can produce high in-stream concentrations
Accurate estimations of the pollutant loads requires sampling at varying frequencies during storm events and base flow conditions
We present an urban observatory whose purpose is to collect high frequency stormwater quality and quantity data at locations within combined river/stormwater conveyances and storm drain outfalls. These data will be used to quantify the pollutant loads generated from urban stormwater runoff and overland flow.
Northwest Field Canal
Adaptive Sampling and Communication
Base flows represent diverted Logan River water
Canal receives stormwater runoff from residential and commercial zones
Locations for 8 monitoring sites have been selected (4 active at a time). Two types of monitoring sites have been designed: Continuous Canal and Continuous Outfall.
Sites are set up to sample during storm/pollutant loading events.
Each site is equipped with radio, antenna, and programmable datalogger which allow for outfall sites to sample when rain and runoff are observed
Once rain and runoff are observed, a signal is sent to continuous canal sites to start sampling based on changes in in-situ values.
Surrogate Relationships for TSS and TP
Map of Northwest Field Canal Study Area
Regression methods will be explored to correlate data monitored at high-frequency (turbidity, conductivity, etc.) with TSS and TP values upon the completion of the 2016 sampling season.
Urban observatory is capable of collecting high-frequency data and automated samples pumped through the entire range of indicator variable values.
upstream surrogate relationships will be subtracted from downstream relationships to quantify total stormwater contributions.
Observatory Infrastructure
Flowchart of observatory’s monitoring and sampling logic
Continuous Canal Sites:
Continuous Outfall Sites:
Multiparameter water quality sonde (pH, DO, conductivity, temperature, and fDOM)
Turbidity sensor
Pressure transducer
Automated sampler with 24 1-liter sample bottles
Tipping bucket rain gage
Programmable datalogger, radio, antenna, and solar panel with charge controller
Side looking ADVM for flow measurements (200 South)
Area velocity flow sensor and module
Automated sampler with 24 1-liter sample bottles
Tipping bucket rain gage
Programmable datalogger, radio, antenna, and solar panel with charge controller
Continuous Canal Site Design
Continuous Outfall Site Design
Results from 2015
Sampling and data collection logic were tested
17 separate storm events were sampled
Adaptive sampling and inter-site communications were key to sampling through the entire range of surrogate values.
Example of Data Collected from Storm Event and Adaptive Sampling
Preliminary samples have found stormwater to be higher in TSS and TP.
TSS values were similar at the outfall sites, but TP slightly higher at outlet of residential catchment.
Side Looking ADVM (200 South)
Continuous Outfall Site West of Sam’s Club
300 South Continuous Outfall Site
200 South Continuous Canal Site
1800 North Continuous Canal Site
Boxplot of 2015 TP values at the 4 monitoring sites
Boxplot of 2015 TSS values at the 4 monitoring sites
Broader impacts
Automated Sampler and Equipment inside Stormbox
Radio, Datalogger, and Charge Controller
The results of this research will provide innovative, alternative methods for quantifying TSS and TP in urban stormwater runoff. The urban observatory will provide continuous datasets for better understanding the important factors that govern pollutant loading during storm events.
Turbidity Sensor
Area-Velocity Flow Module
Water Quality Sonde